1. Field of the invention
The present invention relates to a radar apparatus.
2. Description of the Prior Art
A recent radar apparatus used for a vehicle or an industrial field has to be miniaturized since it has to be mounted on a bumper of the vehicle or a grill portion.
However, the radar apparatus used for the vehicle generally is designed to have a very precise and complicated RF front end structure with 24 to 77 GHz frequency bands, and this practically constraining its miniaturization.
Recently, lots of techniques have been developed to further miniaturize the size of the radar apparatus with this unavoidably complicated design structure.
A multiple transmission channels are adopted to improve the feature of the radar apparatus. The multiple transmission channel structure requires an additional reference transmission signal necessary to calculate a difference between a transmission signal and a reception signal.
Therefore, the radar apparatus implementing the multiple transmission channels requires at least one additional transmission RF port for the reference transmission signal to calculate the difference between the transmission signal and the reception signal in addition to transmission RF ports as many as the number of the multiple transmission channels.
That is, at least N+1 transmission RF ports are necessary for implementing N transmission channels.
This constrains miniaturization of the radar apparatus and also prevents an implementation of a desired number of transmission channels, or causes a disadvantage of necessity for an additional circuit such as an active circuit to implement an additional transmission RF port synchronized with the other transmission channels.